The invention is in the field of spectrum analyzers and specifically relates to a device for analyzing fast signals, e.g. signals of transient nature, whose time duration is short as compared to the normal sampling rate of a spectrum analyzer, and also relates to devices for capturing and time-stretching signals of a very short duration.
There are many circumstances in which it is desired to analyze a signal of a transient nature, that is, a signal which occurs perhaps only once, and for a brief period of time. Closely related are the problems of analyzing a short time duration signal which may occur periodically, but with a relatively long time duration between occurrences, and of analyzing a very short portion of any signal. In analyzing signals of this type, not only is the wave shape of the signal important, but frequently information about the frequency content of the signal is desirable. If the signal is of very short duration, the problem of acquiring and performing measurements of it is difficult. One prior art approach has been to digitize the signal and to store the digital information. The signal can then be repeatedly examined, and further processing can be performed on it at a slower rate. However, this requires a very high digitizing rate, and this is expensive for signals of very short duration, and may even be impossible for extremely short signals. Another prior art approach uses devices such as storage oscilloscopes to record and hold the fast signal. However, this has the disadvantage that the signal is merely stored on the CRT face and can not be further processed except by manual translation of the stored image into numerical information. Such manual translation is expensive, and subject to human error. It is desirable therefore to provide for acquiring a signal whose time duration may be very short, and for analyzing the acquired signal in a manner which is efficient, error-free and relatively inexpensive.